workshop on precipitation measurements madrid 23-27 september 2002 an intercomparison of gauge,...
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WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
AN INTERCOMPARISON OF GAUGE, RADAR AND SATELLITE RAINFALL IN THE TROPICS
A. J. Pereira Filho1, A. Negri2 and P. T. Nakayama3
1USP, São Paulo, Brazil2NASA/GSFC, MD, USA
3DAEE, São Paulo, Brazil
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
STUDY AREA
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
GAUGE DATA
ACCUMULATION
1000 UTC - 1000 UTC
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
SPWR DATA5 Minutes Scans3-km CAPPI4-bit Rainfall Rates2-km x 2-km Resolution
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
SATELLITE DATA
GOES-East IR30 Minute Scans2-bit Rainfall Rates (CST)0.0, 2.6 and 18.9 mm h-1
4-km x 4-km Resolution
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
GAUGE X RADAR
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
GAUGE X RADAR
G = Gauge Mean
RG = Buck Ratio
RI = Mean Ratio
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
GAUGE X RADAR X SATELLITE
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
GAUGE X RADAR X SATELLITE
0.01
0.1
1
10
100
0.01 0.1 1 10 100
Mean Rainfall (mm)
ST
D (
mm
)
SATELLITE
RADAR
GAGE
R2=0.96
R2=0.88
R2=0.87
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
RADAR X SATELLITE
Highest +
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
RADAR X SATELLITE
Highest -
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
RADAR X SATELLITE
Highest Difference
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
RADAR X SATELLITE
Stratiform
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
RADAR X SATELLITE
Maximum Areal Mean
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
RADAR X SATELLITE
Sampling and 2-bit Info Content
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
RADAR X SATELLITE
Total Rainfall
1 = Ground Clutter Filtering (2 and 3)4 = Grind Clutter Contamination5 = Range Effect7 = Signal Processing
WORKSHOP ON PRECIPITATION MEASUREMENTSMADRID 23-27 SEPTEMBER 2002
CONCLUSION
•Large rainfall events have relative small spatial variance
•Small rainfall events have relative large spatial variance
•Differences Radar x Satellite 70% due to phase
•Satellite less susceptible to systematic errors
•Limitations:
Satellite: Information content and sampling
Radar: Electronics, ground clutter, range effect, ...
Gauge: Representativity
•Next Step: Integration